1. Field of the Invention
The present invention relates in general to a vehicle control apparatus operable to control an automotive vehicle during a shifting action of an automatic transmission of the vehicle, and more particularly to a vehicle control apparatus which is operable, upon generation of an engine-output command requiring an engine of the vehicle to provide a desired output during a shift-up action of the automatic transmission initiated in the absence of the engine-output command, to efficiently establish an output torque or drive torque of the engine according to the engine-output command, while preventing or minimizing a racing phenomenon of the engine, an excessive increase of a thermal load of frictional coupling devices of the automatic transmission, or an excessive shifting shock of the automatic transmission.
2. Discussion of Related Art
In the field of an automotive vehicle, there is widely used an automatic transmission of a type arranged to transmit an output of an engine to drive wheels of the vehicle, at a selected one of a plurality of speed ratios by establishing a corresponding one of operating positions of the automatic transmission, by selecting a corresponding one of different combinations of operating states (engaged and released states) of a plurality of frictional coupling devices incorporated in the automatic transmission. JP-A-7-247873 discloses an example of a control apparatus to control an automotive vehicle provided with an automatic transmission of this type, which apparatus includes shift control means for shifting the automatic transmission by engaging one of a plurality of frictional coupling devices while releasing another of the frictional coupling devices, and engine-torque-increase restricting means operable upon an operation of an accelerator pedal during a shift-up action of the automatic transmission to reduce its speed ratio (input speed/output speed), which shift-up action is initiated while the accelerator pedal is in the non-operated position. The engine-torque-increase restricting means is arranged to restrict an increase of the engine torque irrespective of the operation of the accelerator pedal, to prevent a shifting shock of the automatic transmission due to a racing of the engine, until the frictional coupling device to be engaged to effect the shift-up action has been filled with a pressurized working fluid and brought into a state capable of transmitting a torque.
The conventional vehicle control apparatus described above is not arranged to control the engine torque in an inertia phase of the frictional coupling device to be engaged to effect the shift-up action of the automatic transmission, in which the torque capacity of the frictional coupling device is gradually increased. Instead, this vehicle control apparatus is arranged to control the hydraulic pressure applied to the frictional coupling device in question, according to an angle of opening of a throttle valve, for thereby preventing the engine racing, in the inertia phase of the frictional coupling device. However, this hydraulic pressure control inevitably suffers from a delayed control response of the hydraulic pressure. Further, the frictional coupling device in its inertia phase is required to provide the torque capacity including an inertia torque due to a speed variation of an input rotary member of the frictional coupling device. Accordingly, the conventional vehicle control apparatus undesirably suffers from an increase of an amount of slipping of the frictional coupling device, a tendency of the engine racing, an excessive increase of the thermal load and a consequent deterioration of durability of the frictional coupling device, and an increase of a shifting shock of the automatic transmission due to an excessive increase of the engine torque.